Method of production of a cable press connection

ABSTRACT

A method of forming a press connection between at least two adjacent cables ( 6, 7, 10 ), by pressing a sleeve ( 5 ) enclosing at least two cables ( 6, 7 ) by compression forces (K), acting approximately radially inwards on two opposing circumferential sections across more than 90 degrees of the circumference in each case, until a flowing of the sleeve material takes place.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of forming a compression connectionbetween at least two adjacent wire cables by compressive deformation ofa sleeve enclosing the at least two wire cables. Moreover, the inventionrelates to a method of forming a compression connection of a cable bymeans of a sleeve enclosing the cable in accordance with the preamble ofclaim 4. The invention, furthermore, relates to an apparatus forpracticing the previously described methods.

2. The Prior Art

For the formation of such compressive connections it is known to usemetal sleeves the cross sectional contour of which consists of twosemicircular sections connected to each other by two straight sections.To form a loop, two cable strands, for instance, are inserted into sucha sleeve. The sleeve is thereafter pressed under high pressure into acircular or oval shape. As a result of the pressing operation the twocable strands are pressed against each other and against the interiorwall of the sleeve such that a sufficiently high frictional force isbuilt up between wire cables and sleeve to prevent the connection frombeing severed even under the effect of high tensional forces. Tostrengthen the frictional lock further, it is known sectionally in itsstraight sections to reinforce the thickness of the wall of the sleevein the direction of the interior of the wall in order to attain anembracement as large as possible of the two wire cables.

The essential drawback of all the prior art compressive deformations maybe seen in the fact that the sleeves requires post-processing. Also, thecables frequently break immediately adjacent to the transition betweenthe sleeve and the cable. Moreover, the sleeves have hitherto beencomplex and expensive.

OBJECT OF THE INVENTION

It is an object of the invention to improve the previously describedmethods in respect of functional press connection and their costs and topropose an apparatus suitable for practicing the methods.

BRIEF SUMMARY OF THE INVENTION

In accordance with the invention and proceeding upon the above-describedmethods, the object is accomplished by the sleeve, for its pressuredeformation, being subjected at two opposite circumferential sections bymore than 90° of circumference, to at least approximately radiallyinwardly directed compressive forces until the sleeve material begins toflow.

In this connection, it is useful by the pressure deformation to impartto the sleeve a polygonal, preferably hexagonal cross-sectional contouror, alternatively, a lenticular cross-sectional contour. In this manner,the sleeve is deformed from more than two directions. The deformationresults in flowing of the sleeve material so that the tensile strengthof the wire cables is completely maintained. The lenticularcross-sectional contour may be of non-uniform inclination, i.e. thecross-sectional configuration may be similar to that of an optical lenswith a pointed edge or the cross-sectional configuration may be of aflat oval shape.

The stability may be usefully supplemented by insertion of a fillerelement prior to the pressure deformation of the sleeve.

Where a hexagonal cross-sectional contour is used, it is possible toround off its corners. In the case of a lenticular cross-section, thecenter arcuate section may be formed as a circular segment.

For supplementing the pressure deformation and for saving material, thecross-sectional contour of the interior of the sleeve may correspond tothe number of wire cables to be inserted. In case two adjacent wirecables are pressure deformed an oval sleeve interior is recommended.

Sleeves of metallic materials, for instance aluminum, may be used in allinstances; but non-metallic materials which preferably are capable offlowing may be used as well.

DESCRIPTION OF THE SEVERAL DRAWINGS

The novel features which are considered to be characteristic of theinvention are set forth with particularity in the appended claims. Theinvention itself, however, in respect of its structure, construction andlay-out as well as manufacturing techniques, together with other objectsand advantages thereof, will be best understood from the followingdescription of preferred embodiments when read in connection with theappended drawings, in which:

FIG. 1 schematically depicts, in a half-open state, a pressure toolconsisting of an upper tool and a lower tool including an inserted notyet compressed oval sleeve which is embracing two adjacent wire cables,the upper and lower tool each being provided with recesses which in amirror image are alike and which together enclose a hexagonal contour;

FIG. 2 depicts the lower tool of FIG. 1 by itself;

FIG. 3 shows a lower tool according to FIG. 2, but provided asemi-lenticular recess;

FIG. 4 shows the sleeve of FIG. 1 by itself;

FIG. 5 is a cross-section of the sleeve shown in FIG. 1 aftercompressive deformation including the two compressed wire cables;

FIG. 6 is a representation, according to FIG. 5, of a pressed connectionwith an inserted or compressed filler element;

FIG. 7 is a representation according to FIG. 5 of three press connectedwire cables;

FIG. 8 is the embodiment of FIG. 7 with inserted filler elements; and

FIG. 9 is a top elevational view of a loop compressive deformation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The representation according to FIG. 1 shows an open press tool whichconsists of an upper tool 1 and a lower tool 2 which are provided withidentical, in mirror image, recesses 3, 4 which together circumscribe ahexagonal contour. Each of the two recesses 3, 4 thus corresponds tohalf a hexagon, that is to say that in cross-section it represents aquadrilateral with one pair of sides parallel (hereafter “trapezium”),as may be seen in FIG. 2 in connection with the lower tool 2. As analternative to the mirror-image embodiment of the recesses 3, 4 thetools of FIGS. 2 and 3 may be combined such that the lower tool 2corresponds to half a hexagon, whereas the associated upper tool 1 isprovided with a recess 3 configured as half a lens. If desired, thecross-section of the sleeve below and above may respectively correspondto half a hexagon and half a lens. Other deviations and variants arepossible.

A sleeve 5 is inserted into the recess 4 of the lower tool 2. The sleeve5 is of oval cross-section as shown in FIG. 4. This cross-sectionalconfiguration may be composed of two semi-circles which are connected toeach other by straight center sections. However, the rounded section mayalso be formed by an evolute. The wall thickness s of the sleeve 5around its circumference as well as length is substantially uniform.

According to FIG. 1 the oval sleeve 5 embraces two wire cables 6, 7positioned adjacent each other which may form a section of a common loop8 as shown in FIG. 9.

FIG. 5 depicts a cross-section of the sleeve 5 with the two wire cables6,7 pressure deformed by the press tool according to FIG. 1. As a resultof the pressure deformation, the sleeve 5 has attained an out contourconforming to the recesses 3, 4 of the upper and lower tools 1, 2. Bythe pressing surfaces forming sections of a hexagon, the sleeve 5 shownin FIG. 1 at its opposite rounded sections by the closing action of thepress tool is subjected to approximately radially inwardly directedcompressive forces K around more than 90° of circumference. The salientpoint of the invention is that the compressive forces affecting thesleeve 5 during the closing action of the press tool are introduced intothe sleeve 5 as radial forces not only in the upper-most and lower-mostcross-sectional point but to attain a radial orientation of thecompressive forces K over a larger circumferential range. This isrealized by the hexagonal configuration of the pressure chamber 3,4receiving the sleeve 5 or, alternatively, by lenticularly configuredpressing chamber half of which is shown in FIG. 3 at reference character4 a as associated with the lower tool 2. Half the lens contour 4 a isformed, deviating from a semi-circular configuration, is by a flatconcave contour.

The compressive deformation is carried out such flowing of the sleevematerial is initiated. This results in a positive connection between thesleeve and the wire cable. Where voids occur in consequence of theconfiguration and/or of the number of the wire cables to be connected toeach other, which cannot be closed by the flowing of the sleeve materialit is useful prior to pressing operation to insert at least one fillerelement 9 into the sleeve 9. The filler element 9 may also be introducedat any location for increasing the stability. The filler element may,for instance, be one or more wires. The position of the filler elements9 between the wire cables 6, 7 may be fixed by adhesives or grease.

FIG. 6 depicts two wire cables 6, 7 pressed together with fillerelements 9.

FIG. 7 depicts a press connection between three wire cables 6, 7, 10. Nosleeve 5 of oval configuration is required for this compressivedeformation; a simple tube or tube section could be used, or a sleevethe cavity of which is of even-sided triangular cross-section and theouter contour of which may even be circularly configured.

FIG. 8 also shows three press deformed wire cables 6, 7, 10 thecompressive deformation was carried out with filler elements 9, however.

In order to created a softer transition for the compressively deformedwire cables 6, 7 10 at at least one end of the sleeve 5, it may beuseful to apply the compressive forces K at only part of the length ofthe sleeve 5 the overall length of which is shown by “l” in FIG. 4. Forthis purpose, a press tool a 1, 2 is preferably used the axial length Lof which is less than the axial length l of the sleeve 5 to be pressdeformed. At the end of the sleeve 5 not subjected to pressing forces,this leads to the formation of an annular ridge not shown in detail inthe drawing which prevent a prevents a sharp-edged bend of the wirecable in the area of its exit from the sleeve. As an alternative to apress tool 1, 2 of short configuration, the sleeve 5 to be pressdeformed is not wholly inserted into the press tool 1, 2 so that a ridgeis formed at one end of the sleeve 5 which was not subjected to radialcompressive forces K.

The oval sleeve shown in FIG. 4 may represent a section of a drawn tubeprovided with this cross-sectional contour. But a section of a roundtube subsequently flattened at two opposite circumferential sections 5a, 5 b may also be used as a sleeve.

In order to facilitate the insertion of an end of a wire cable into thesleeve 5, the sleeve may be provided with a chamfer at at least one ofits ends in a manner not shown in detail in the drawings. The chamfer atone end or at both ends of the sleeve 5 prevents a jump in the stiffnesswithin the wire cable 6, 7, 10 thus ensuring the durability of the cableconnection or compressive connection with one end piece of the sleeve.Tensile tests which have been performed have shown that before failureoccurs at a compressive connection or the cable breaks at the transitionbetween sleeve and exposed cable, the wire cable breaks in its centereven though only one Compressive connection with one sleeve is used. Ajump in the stiffness at the transition between the sleeve 5 and theexposed cable 6, 7, 10 is also realized by an application of compressiveforces K over only part of the length of the sleeve 5 since in thismanner no flow is induced in a terminal section of the sleeve 5, and theterminal section correspondingly embraces, and is filled by, the cable.The formation of a chamfer and of a collar may be carried out asalternatives or in combination.

The special shape of the upper tool 1 and of the lower tool 2 avoids anycomplex further machining of the compressively deformed sleeve 5 in botha lenticular and hexagonal cross-sectional configuration of the presstools 1, 2, since no sharp edges occur at the points of impact of thepress tools 1, 2. In case the outwardly and inwardly flowing material ofthe sleeve does not completely fill the hexagonal cross-sectional mold,the resultant shape will be a desirable rounded hexagonalcross-sectional shape without any formation of burrs, so that subsequentmachining becomes unnecessary.

1. A method of producing a compressive connection between at least towadjacent wire cables (6, 7, 10) by compressive deformation of a sleeve(5) embracing the at least two wire cables (6, 7), characterized by thefact that for its compressive deformation the sleeve (5) is impacted byinwardly directed substantially radial compressive forces (K) at twoopposite circumferential sections over more than 90° of circumferenceeach.
 2. The method according to claim 1, characterized by the fact thatby its compressive deformation the sleeve (5) acquires a polygonal,preferably hexagonal cross-sectional contour.
 3. The method according toclaim 1, characterized by the fact that by its compressive deformationthe sleeve (5) acquires a lenticular cross-sectional contour.
 4. Amethod of producing a compressive connection between a wire cable (6, 7,10) and a sleeve (5) embracing the wire cable 6, 7, 10) by compressivedeformation, whereby the sleeve at two opposite circumferential sectionsover more than 90° of circumference is subjected to inwardly directedsubstantially radial compressive forces (K) until the sleeve materialbegins to flow, characterized by the fact that by its compressivedeformation the sleeve (5) acquires a lenticular cross-sectionalcontour.
 5. The method according to claim 4, characterized by the factthat prior to compressive deformation at least one filler element (9) isinserted into the sleeve (5).
 6. The method according to claim 4,characterized by the fact that the compressive forces (K) are applied toonly a partial length of the sleeve (5).
 7. The method according toclaim 4, characterized by the fact, that for the compressivedeformation, in particular of at least two adjacent wire cables (6, 7),in particular for the compressive deformation of a loop, a sleeve (5) ofsubstantially oval cross-section and substantially uniform wallthickness (s) is used.
 8. The method according to claim 7, characterizedby the fact that the sleeve (5) used is a section of a tube made ofround configuration subsequently flattened at two oppositecircumferential sections (5 a, 5 b).
 9. The method according to claim 4,characterized by the use of a sleeve (5) provided with a chamfer at atleast one of its two ends.
 10. The method according to claim 4,characterized by the use of a sleeve of metallic material.
 11. Themethod according to claim 4, characterized by the use of a sleeve ofnon-metallic material.
 12. An apparatus for practicing the method of oneof the preceding claims, characterized by a two-part press tool forcompressively deforming the sleeve (5), the upper and lower tool (1, 2)of which are each provided with a recess (3, 4) identical in mirrorimage which together embrace a hexagonal or lenticular contour.
 13. Theapparatus or claim 12 for practicing the method, characterized by thefact that the axial length (L) of the press tool (1, 2) is less than theaxial length (l) of the sleeve (5) to be compressively deformed.